Life saving elevator



June 19, 1951 TARAslUK 2,557,483

LIFE SAVING ELEVATOR Filed Oct. 26, 1949 5 Sheets-Sheet 1 IN VEN TOR.

i BY 6 June Filed Oct. 26. 1949 M. TARASI UK LIFE SAVING ELEVATOR 5 Sheets-Sheet 2 JNVENTQR. 0426! 722/2291 41%;,

M. TARASIUK LIFE SAVING ELEVATOR June 19, 1951 3 Sheets-Sheet 3 Filed Oct. 26, 1949 IN V EN TOR.

1 74mm?! 7&izzaazz/, BY

Patented June 19, 1951 Nrrso STATES 1* OFFICE Claims. (Cl. 188-64) The present invention relates to life saving elevators and has for its main object the provision of an elevator of a comparatively simple construction and operation. The principal object of the invention is the provision of a safety elevator, portable in its nature, designed for a mechanical operation, and which may be capable of suspension inwardly of a structure, such as an apartment, hotel or school building or a factory, with the carrying portions of the elevator hung outside of a structure and extended through a window or like opening, whereby a person may be safely downwardly carried along the outer face of a structure walhto be used in case of fire or other emergency, when the egress from the structure is otherwise blocked or impeded. V Another object of the present invention is the provision in an elevator of the type indicated, of a looped cable shiftable upon and passed over a pulley, with a person supporting saddle attached to each end of the cable, having a principal brake in association with the pulley, and a secondary brake coacting with each end of the cable, and wherein the two brakes are capable oflocking the cable for preventing its shifting notwithstanding the weight of a person while in the saddle, with means operable by a person in the saddle for intermittently releasing said principal brake and thereby for controlling gradual shifting of the cable upon the pulley in order to eifect gradual, unprecipitous descent of a'pers'on while in the saddle. v A further object of the present invention is the provision, in an elevator of the type hereinabove indicated, of means for controlling the said sec" ondary brake by the very weight of a person in the saddle in order to transfer the action of the said secondary brake exclusively upon the end of the cable not under the weight of a person and for entirely freeing from the action of said secondary brake that end of thecable which carries a person occupying the saddle.

With the above general objects in view and others that will appear as the invention is :better understood, the same consists in the novel construction, combination and arrangement of parts hereinafter more fully described, illustrated in the accompanying drawing and pointed out in the appended claims.

In the drawings forming a part of this application, and in which like designating characters referto corresponding parts throughout the sev: eral views: 7 '....,Fi 1 i a f n elevational view of the present device;

Fig. 2 is a side elevational view thereof; I

Fig. 3 is a fragmentary, rear elevational view;

thereof;

Fig. 4 is an enlarged front view of the present device, partly in elevation and partly in section,

showing the secondary brake in a neutral position when neither end of the cable is under a load.

n i n;

p Fig. 5 is a cross-sectional view, taken on line illustrating the position of the mechanism of the secondary brake when one end of thecable is under a tension due to the weight of a person carried thereby;

Fig. '7 is a cross-sectional view, taken on line 1-4 of ig. 6; and p Fig. 8 is across-section on line 88 of Fig. 2.

Referring to the present drawings in detail there is shown cross-bar l llfwhich is interposed and firmly clamped between a pair of downwardly depending arms H, by means of bolt I2, which is passed through said cross-bar I0 and said arms ll. Staple-l3, or similar engageable fastener, is firmly, rigidly anchored to said cross-bar Ill, to receive in turn looped chain or cable I4. The latter is passed over a beam or other support, not shown, preferably located within a structure, for supporting thereon the entire device, as well as a person employing the same in order to be carried thereby out of the structure along the outer face of its wall. V

The ends of said cross-bar l0 extendbeyond the side'edges of said arms I l. .Affixed to one end of said cross-bar mfalong one of its faces, by' means of a pair of screw bolts I5, is adownward ly extending arm 16.. 'Pivotally supported upon the lower end of said arm l6, by meansofpin I1 is brake lever l8.

Interposed between said arms H, and sup ported for a rotary movement upon shaft 19, is pulley 28, from one face or which an integrally formed, reduced drum 2| extends. Said brakelever l8 has along its upperedge arcuate recess 22 within which lowermost portion of the periphery of saiddrum '2[ is received for causing the adjacent body portion of said brake lever l8 to bear against said drum 2|, as best shown in Fig. 8.

Attached by its lower end to the opposite end ofsaid brake lever I8 is coil spring 23, the upper end of .which is afiixed to bolt 24, extending downwardly from the opposite, reduced end of said cross bar l0. Said coil spring is normally under a strong compression for maintaining brake lever iii in a strong frictional engagement with the periphery of drum 2| for normally preventing a rotary shifting movement of said pulley 20.

To overcome the leverage of brake lever [8 due to the action of spring 23 thereon, auxiliary lever 25 is provided. The latter lever is pivoted upon pin 26 at the inner end of the former. Said inner end of said auxiliary lever 25 is positioned for angular shifting movement within transverse recess 21 made adjacent the front face of rear arm ll. Adjacent the connecting point of said coil spring 23 with said brake lever IE, but intermediately the said point and pin ll, said brake lever I8 is pivotally connected with said auxiliary lever 25 by means of screw 28. The outer free end of said auxiliary lever 25 is extended past the adjacent end of brake lever I8, and there has a connected cord 29. When said cord is pulled into a downward direction the same will cause a downward, angular shifting movement of said auxiliary lever 25 upon its pivot 26. The downward shifting movement of said auxiliarylever 25 will in turn cause said brake lever 18 to angularly shift to the same direction by virtue of the connection between the two levers by pivotal screw 28, against the tension of coil spring 23 upon said latter lever for disengaging the frictional contact thereof with drum 2|. effect will permit pulley 28 to freely rotate upon shaft l9, all for the purpose hereinafter specified.

Passed over pulley 20 is the loop of cable 30. The two ends of cable 30 leaving the said loop and said pulley 20 are crossed therebelow, as at 3|, and then passed through a pair of downwardly diverging bores 32, made in guide bar 33. Said guide bar 33 guides the two ends of cable 38 below their cross point 3| in a downwardly diverging direction for the purpose of locating said cross point 3| at a comparatively short distance of the periphery of pulley 20. The effect of this arrangement is to bring about almost complete entwining of the cable loop around said pulley with the ultimate result of causing cable 38 to shift with pulley 20 when the latter is capable'of a rotary movement on disengagement of brake lever l8 from drum 2|, and not to merely slide upon pulley 20 independently thereof, and conversely, not to permit-the shifting of cable 30 when pulley 20 is still held by the action of said brake lever it upon drum 2|. Another action of said guide bar 33 upon the ends of cable 38 leaving bores 32 is to properly distance them preparatory to the said ends of cable 30 having been received into the auxiliary brake hereinafter described.

Along the rear face of front arm H and adjacent the lower end thereof, said arm H is provided with recess 34 within which the front edge of said guide bar 33 is receivable. The rear edge of said guide bar 33 is in contact with the front face of rear arm H, as is seen in Fig. 2. Screw bolt '35 is passed through said guide bar 33 and said arms I I in a transverse relation for clamping said guide bar 33 within said arms H. Adjacent the front edge of said guide bar 33, and centrally thereof, the same is provided with downwardly diverging recess 38, within which the upper end of oblong plate'31 is positioned for angular swinging movement within recess 36, in either directiOn, upon said bolt 35, which constitutes a pivot therefor. For further maintaining said guide bar 33 in a rigid stationary relation with arms II a pair of screws 38 are passed through front arm I l and engage said guide bar 33.

This latter The auxiliary brake acting intermittently upon two ends of cable 30 includes a substantially U-shaped cradle 38 of an oblong formation. The front edge thereof is in an alinement with the front edge of said guide bar 33. Said cradle 38 has recess 39 along its rear edge oppositely disposed of the rear arm I I. Receivable within said recess 39 in a longitudinal relation with said cradle 38 is carriage 40 the ends of which are spaced from the adjacent solid ends of said cradle 38, permitting a shifting movement of said carriage 40 within recess 38 and in a longitudinal relation with said cradle 38.

The lower end of said plate 3'! is passed downwardly along the inner face of the outer edge of said cradle 38, and centrally thereof, and is there pivoted upon screw 4|, the outer end of which is engaged by nut 42 and lock nut 43. Said screw 4! 'is passed through the central portion of said cradle 38. The head of said screw 4| bears against-said plate '31 and maintains the latter in contactual engagement-with said cradle 38. Carriage 40 is provided with recess 44 for accommodating therewithin the head of said screw 4| and said plate 37 and for permitting shifting movement of said carriage 40 within said cradle 38 without interference from said screw 4| and said plate 31.

Connecting links 45, pivotally affixed to said guide bar 33 and cradle 38 along their front faces by means of screws 46,'coact with said plate 31 for suspending said cradle 38 for rocking action. By virtue of the fact that plate 31 engages cradle 38 from the rear face thereof and said links 45 engage said cradle 38 from the opposite, front face thereof, said cradle, as well as the entire assemblyof the said auxiliary brake, is supported in a proper horizontal position.

It is noted that the lower end of the front arm terminates short of the plane of the upper faces of said cradle 38 and of said carriage 40, while the rear arm H extends by its lower end well below the plane of the lower faces of said cradle 38 and carriage 40.

Coacting with the lower end of said rear arm II and rearwardly thereof is L-shaped lever 41, the lower horizontal leg portion of which is directed forwardly and carries cross-piece 48, affixed to said leg portion by means of screw 49.

The upper end of said lever 41 is pivoted to the lower end of said rear arm H by means of pivot screw 58, which permits said lever 41 to make rocking movement in lateral directions. Rigidly engaging the upper termination of said lever 41 and above the pivot is threaded pin 5|, engaging by its inner end carriage 40 and passing through arcuate slot 52 made in the lower end of rear arm II. From this arrangement it will be readily apparent that when pressure is applied to one end of cross-piece 48 in one direction, thereby causing the lower end of lever 41 to shift in the same direction, the upper end of said lever 41 above pivot 50 will be caused to shift in the opposite direction, thereby shifting carriage 40 into the last mentioned direction, slot 52 permitting said pin to shift therewithin during the rocking movement of said lever 41.

Adjacent each end, said carriage 40 is provided with a longitudinal recess 53 open along the lower face of said carriage 48 for insertion of brake parts. Plate 54 attachable to carria e 40 along its lower face by means of screws 55 constitutes a closure of the two recesses 53 for maintaining therewithin in an assembled position the brake parts presently described. I

50 with respect of said cradle- 38.

The outer end of each recess 53 is outwardly flaring on a horizontal plane, for receiving therewithin Stationary brake shoe 56, with which shiftable brake shoe 5? coacts. The opposite end of each recess receives cam 58 positioned within the reduced inner end of each recess 53. Interposed between said shiftable brake shoe 57 and said cam 58 is coil spring 59, which normally urges each shiftable brake shoe 51 towards each of said stationary brake shoes 56, for normally clamping ends of cable passed therebetween. Said stationary brake shoe 56 and the cooperating shiftable brake shoe 5! each has semi-circular, vertical, complementary groove for accommodating therewithin cable 38, the diameter of the two 0pposed cooperating grooves being smaller than the diameter of said cable 38 in order that the two shoes may exert pressure upon the cable.

Said cam 58 is provided with an outwardly extended handle or knob 65, the manual turning of which shifts cam 58 in a greater or lesser contact with coil spring 59 and thereby regulates the degree of tension thereof upon shiftable brake shoe 5! against which it bears, as is clearly seen in Figs. 4, 5 and 6.

Said carriage 40 and plate 54, adjacent each of their ends, are provided with alined openings 6| which are also in a substantial alinement with the-complementary grooves made in said stationary brake shoe 56 and said shiftable brake shoe 51. Through said openings 6! the ends of cable 30 are passed, as is clearly indicated in Figs. 4 and 6.

Associated with each end of said carriage 4a is a pair of rods 62, which are accommodated within horizontal, spaced bores in the ends of said carriage 49, and like alined bores in the adjacent end portions of cradle 38, in the two sets of which bores said rods 82 are capable of sliding movement longitudinally of said cradle 38 and said carriage 40. The inner ends of said rods 62 are passed through said stationary brake shoe 56 at each end of carriage i9, and the outer ends of said rods 62 are capable of bearing against stop screws 63, driven in a vertical direction through and adjacent the ends of said cradle 38. If cradle 38 is made of metal, stop screws 63 may be entirely eliminated.

The ends of said cable 30 passing plate 55 are directed toward the longitudinal center of arms II, and are passed through openings t4 made adjacent each end of said cross-piece 48. In the neutral position of cable at, as seen in Figs. 1 and 4, the ends of cable 39, below the cross point 3|, substantially assume a rhombus-like formation, they being spaced farthest apart at points coincidental with openings SI and said brake shoes 56 and 57. Below cross-piece 48 the ends of cable 38 assume a parallel spaced relation.

Connecting pins 65, passed through slots 66 made in the front strip of said cradle 38, engage carriage all, as best shown in Fig. 1. Said pins 65 limit the shifting movement of said carriage It may be noted that said rods 62 and pins 65 constitute the only connecting means between said carriage 36 and cradle 38, and permit shifting movement of said carriage 50, in a longitudinal direction, with relation to said cradle 38.

Attached to each end of cable 30 is saddle 51, made in a form of a seat or harness, capable of supporting a person therein. For the proper operation of the device saddle 61 upon one end of cable 36 must necessarily be in the proximity the saddle upon the other end of cable 39 is not in the proximity of the device. In fact, said other end of cable 30 must be of a length corresponding to the distance between the point of location of the present device and the ground, so that the cable may be of proper length, capable of carrying a person from the point of location of the device to the ground.

In the neutral position of the said auxiliary brake, best shown in Fig. 4, carriage A0 remains in equidistance from the adjacent ends of cradle 38. brake coil springs 59 exert equal pressure upon shiftable brake shoes 51. The latter not only clamp the ends of cable 30 remaining within shoes 56 and 51, but also bear against the adjacent ends of rods 62 for retracting them against stop screws 63. Rods 62 are of such length as to not interfere with the operation of shiftable brake shoes 5! for clamping the ends of cable 30 remaining within shoes 56 and 57. In that neutral position of the auxiliary brake, connecting pins 65 are in a central position with relation to slots 66, as is seen in Fig. 1. When the device is not in use, said auxiliary brake assumes the neutral position hereinabove described. That neutral position is brought about by springs 59 exerting equal pressure upon 'shiftable brake shoes 51 and the pressure of the latter upon the adjacent ends of rods 62 to maintain said rods 62 in a retracted position. It will therefore be seen that in said neutral position of the auxiliary brake said rods 62 constitute the means for rigidly connecting carriage 40 with cradle 38 preventing either from shifting into any direction.

When one end of cable 30 is weighted by a load of a descending person occupying one saddle 61 at one end of said cable 3!), in that very moment the rhombus-like relative position of the two ends of the cable hereinabove described and by them assumed while in a neutral position, intermediately of said guide bar 33 and cross-piece 48, undergoes an instant change for actuating the auxiliary brake for the purpose of inducing the latter to release from its engagement the weighted end of cable 30 and to simultaneously increase its clamping pressure upon the opposite free end of cable 30.

If it be assumed that the left end of cable 30, as viewed in Fig. 6, supports the weight of a descending person thereon, the angular position of the left end of cable below plate 5 assumes a vertical position. The weight carried by the left end of cable 30 also tends to urge the portion of said latter end of the cable, disposed above carriage 40, to assume a vertical position. As a result of said last named tendency said left end of cable 38 exerts pressure upon the body portion of said carriage All, adjacent opening 5| for shifting carriage 46 into the direction toward the other endof cable 33. Due to the connection between carriage ii) and cradle 38 through pins 65 the last mentioned shifting of carriage 4B is imparted to cradle 38. The tendency of the portion of the left end of cable 30 disposed between carriage All and guide bar 33 to assume a vertical position is counteracted however by plate 3? and connecting links 45, which, having been shifted to the maximum extent towards the right do not permit further shifting of said cradle 38 and do not allow the angular position of the left end of cable 30, disposed above carriage 60 to assume a vertical position. The angular shifting movement to the right of said plate 3'! and conof the device, readily accessible to a person, while 15 meeting links 45, when carriage 40 and cradle 38 In that neutral position of the auxiliary have shifted to theright-by the actionco'f the left end of cable 30 islimited' byrplatea3l looming in contactwith the'body portion of guide bar 33ad- 'jacent said recess 36, as isseen in Fig. 6.

Simultaneously with the-above described action of the weighted left end of cable 30 upon carriage-4U and cradle 38 for shifting the twotowards the right, saidleft end .of the cable, due to its .assumption of a vertical position below plateEd, exerts lateral pressure upon-cross-piece 48 for shifting theJsame towards the left. This latter :action angularly shifts lever 41 towards .the left, below its pivot'point 50, and shifts the portion of said lever 41 above said pivot point 50 to the right. The shifting movement of the upper end of .said lever 41, above pivot 50, is limited :by pin :51 coming in contact with the body portion of rear arm ll adjacent-the end of :slot 52.

The width of recess 36 is predetermined with relation to the length of slot52, in'such a manner as to permit cradle "38 to shift'to a greater extent than slot 52 permits the shifting of said carriage 49 with relation to said cradle 38. Thus when the left end of cable 30 is weighted by a load, cradle 38 has shifted toagreater distance than carriage 49. As has been mentioned, the maximum shiftingof cradle38 has been limited by plate 3'! coming in contact With the adjacent side edge of guide bar 33 defining recess 36 on the right thereof, as illustrated in Fig. 6. The maximum extent of the shifting of carriage 48 -is regulated by pin coming in contact with the body portion of rear arm ll adjacent the end of slot '52. Body portion of guide bar 33 adjacent recess 36 permits greater shifting of cradle 38 than 'does slot 52 with relation to carriage 40.

Therefore, when carriage '41] and cradle 38 have been brought to their maximum shifted position to the right, as shown in Fig. 6, the right ends of cradle 38 and carriage! will be- :come spaced, with the left ends thereof shifted to the nearest proximity of each other.

By virtue of the fact that the left end of cradle I '38 has been brought to the near proximity of the adjacent 'left'end of carriage 40, rods62 at that end of carriage and cradle are forced against .shiftable brake shoe'5l at the left end of carriage 40, with the opposite rods 62 free. This operation causes left rods 62 to compress spring 59, thereby releasing its action upon shiftable brake shoe 51, thereby completely freeing the weighted end of cable 30 from the operation of the brake. At the right end of the brake, rods G2 having beenrendered inoperative by the shifting of the adjacent right end of cradle 38 with relation to'the right end of carriage 40, do not 20, while assuming a vertical position under the weight of a person, bodily shifts carriage 4G and cradle 38 to the right direction. The action of lever 41 upon carriage do is to retard or hold back said carriage 50 from shifting to the extent to which said cradle 38 has shifted. As a result of these two forces the left end of cradle 38 has been brought to the nearest proximity mittently pulls upon cord 29.

8 with the :adjacent left end of .carriage 40, while at the same time the right end of carriage-40, has been-brought into a retracted position with relation to the adjacent right end of cradle 38.

'The result of the relative shifting movement ,ofzcradle38 with'relation to carriage 40 was to free the weighted end of the cable and to clamp theopposite free end of the cable.

It .isfurther observed that when the opposite end of cable 36 becomes weighted an opposite action of the auxiliary brake upon the two ends of the cable takes place. In that latter event the right end of cable 30 would be caused to assume a verticalposition, thereby shifting the brake assembly towardsthe left, forfreeing the right weighted end of the cable from its opera- .tionand simultaneously exerting braking force upon the opposite free end of the cable.

In the practical use of the device, the whole assembly should preferably be positioned within a structure, and suspended upon a beam or like firm support by means of-cable 14. Both ends of cable 30 should preferably remain also within astructure. The longer end of the cable should however be of a length corresponding to the distance between a window or similar opening in the structure and the ground. A person desiring to use the device will enter into saddle 67 at the shorter end of cable 30 and will suspend himself outside of a Window or similar opening in a structure, manually grasping. cord 29.

At this point it is observed that during the operation of the device the joint action of the principal brake, including drum 2i and pressing brake lever l8 thereon, and of the auxiliary brake including brake shoes .56 and 5? exerting clamping action upon the unweighted end of cable 38 will be sufhcient to prevent shifting of cable 38 upon pulley 20. Thus a person suspended upon'one end of cable 30, and hanging thereon while in saddle 6? outside of a structure and along its outer wall will not cause the shifting of the Weighted end of cable 30 until he inter- This latter action releases drum 2i from the action of the principal brake, permitting rotary shifting movement of pulley 20.

The auxiliary brake should be strong enough in its action to permit gradual shifting of cable 39, but not a rapid one. Cord 29 in the hands of the descending person will intermittently control the principal brake so as to regulate the rate of speed of the descent.

Obviously, when the weighted end of cable 30 shifts downwardly, for bringing its saddle 61 to theground, the opposite end of cable 30 shifts in an upward direction towards the brake and cable controlling device, until that opposite end of cable 30 and its saddle 61 have been brought to the proximity of the device, thereby reconditioning the device for possible renewed use.

While there is described herein a preferred embodiment of the present invention, it is nevertheless to be understood that minor changes may be made therein without departing from the spirit and scope of the invention as claimed.

What I claim as new is:

l. A device of the type described comprising a pulley, a cable extended over said pulley, a primary brake normally maintaining said pulley in a stationary position, a secondary brake, the ends 'of said cable being extended through said secondarybrake, said secondary brake normally engaging both ends of said cable, the ends of said cable being adapted to selectively receive a load weight,

amuse means in said secondary brake for releasing the engagement thereof with the end of said cable which is weighted by a load, the operation of said means being induced by the weight of a load carried by the weighted end of said cable, and means for controlling said primary brake for intermittently releasing said pulley from the operation of said primary brake.

2. A device of the type described comprising a pulley, a primary brake normally maintaining said pulley in a stationary position, a secondary brake positioned below said pulley, a cable extended over said pulley, the ends of said cable being extended through sa d secondary brake for normal engagement thereof by said secondary brake, the ends of said cable below said secondary brake selectively receiving a load weight in a suspended relation, means in said secondary brake for releasing the engagement thereof with that end of said cable which is weighted by the suspended load, the operation of said means being induced by the weight of a load suspended upon that end of said cable, the action of said secondary brake upon the opposite unweighted end of said cable in conjunction with the action of said primary brake upon said pulley preventing the shifting movement of said cable'in the direction of the load, and means for controlling said primary brake for intermittently releasing said pulley from the operation of said primary brake, said last named means being operable independently of said secondary brake, on operation of said last named means said pulley being capable of rotary movement for permitting shifting of said cable in the direction of the load against the action of said secondary brake upon the opposite unweighted end of said cable.

3. A device of the type described comprising a pulley, a cable extended over said pulley, a retaining member disposed below said pulley, the ends of said cable being extended through said retaining member for normally maintaining the ends of said cable in a downwardly diverging mutual relation, engaging members in association with said retaining member for normally engaging each end of said cable, the ends of said cable below said retaining member selectivelyreceiving a load weight in a suspended relation, and means in said retaining member for selectively rendering said engaging members inoperative with respect to the weighted end of said cable, said means being actuable by the load carrying end of said cable as it changes its position from divergentto vertical due to the action thereon by the load weight.

4. A device of the type described comprising a pulley, a cable extended over said pulley, a retaining member disposed below said pulley, the ends of said cable being extended through said 10 retaining member for normally maintaining the ends of said cable in a downwardly diverging mutual relation, clamps in said retaining member for normally clamping each end of said cable,

end of said cable, the load weight upon the weighted end of said cable inducing that end to shift to a vertical position from its normally diverging position, the shifting movement of said one end of said cable inducing the operation of said means.

5. A device of the type desecribed comprising a pulley, a brake for normally preventing the rotation of said pulley, a cable looped around said pulley, a retaining member disposed below said pulley, the ends of said cable being extended through said retaining member for normally maintaining the ends of said cable in a downwardly diverging mutual relation, clamps in said retaining member for normally clamping the ends of said cable, the ends of said cable below said retaining member selectively receiving a load weight in a suspended relation, means in said retaining member for selectively rendering one of said clamps inoperative with respect to the weighted end of said cable, the load Weight upon the weighted end of said cable inducing that end to laterally shift to a vertical position from its normally diverging position, said shifting movement of the weighted end of said cable inducing the operation of said means, the other of said clamps unaffected by the operation of said means in conjunction with the action of said brake upon said pulley preventing a longitudinal shifting of said cable, and means for actuating said brake for inducing a rotary movement to said pulley and for thereby permitting a longitudinal shifting movement of said cable under the influence of the load weight thereon against the action of said last named clamp.

MICHAEL TARASIUK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 266,502 Newhall Oct. 24, 1882 806,837 Ratzer Dec. 13, 1905 FOREIGN PATENTS Number Country Date 330,535 Great Britain 1930 

